Suppose a deaf man denies the existence of sounds because he has never heard them. I put before his eyes a stringed instrument and cause it to sound in unison by means of another instrument concealed from him; the deaf man sees the chord vibrate. I tell him, "The sound makes it do that." "Not at all," says he, "the string itself is the cause of the vibration; to vibrate in that way is a quality common to all bodies." "Then show me this vibration in other bodies," I answer, "or at least show me its cause in this string." "I cannot," replies the deaf man; "but because I do not understand how that string vibrates why should I try to explain it by means of your sounds, of which I have not the least idea? It is explaining one obscure fact by means of a cause still more obscure. Make me perceive your sounds; or I say there are no such things." The more I consider thought and the nature of the human mind, the more likeness I find between the arguments of the materialists and those of the deaf man. Indeed, they are deaf to the inner voice which cries aloud to them, in a tone which can hardly be mistaken. A machine does not think, there is neither movement nor form which can produce reflection; something within thee tries to break the bands which confine it; space is not thy measure, the whole universe does not suffice to contain thee; thy sentiments, thy desires, thy anxiety, thy pride itself, have another origin than this small body in which thou art imprisoned. No material creature is in itself active, and I am active. In vain do you argue this point with me; I feel it, and it is this feeling which speaks to me more forcibly than the reason which disputes it. I have a body which is acted upon by other bodies, and it acts in turn upon them; there is no doubt about this reciprocal action; but my will is independent of my senses; I consent or I resist; I yield or I win the victory, and I know very well in myself when I have done what I wanted and when I have merely given way to my passions. I have always the power to will, but not always the strength to do what I will. When I yield to temptation I surrender myself to the action of external objects. When I blame myself for this weakness, I listen to my own will alone; I am a slave in my vices, a free man in my remorse; the feeling of freedom is never effaced in me but when I myself do wrong, and when I at length prevent the voice of the soul from protesting against the authority of the body.